11561661 has 12 divisors (see below), whose sum is σ = 16732092. Its totient is φ = 7693056.

The previous prime is 11561653. The next prime is 11561681. The reversal of 11561661 is 16616511.

11561661 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 9548100 + 2013561 = 3090^2 + 1419^2 .

It is not a de Polignac number, because 11561661 - 2³ = 11561653 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11561681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5965 + ... + 7661.

It is an arithmetic number, because the mean of its divisors is an integer number (1394341).

Almost surely, 2^11561661 is an apocalyptic number.

It is an amenable number.

11561661 is a deficient number, since it is larger than the sum of its proper divisors (5170431).

11561661 is a wasteful number, since it uses less digits than its factorization.

11561661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2460 (or 2457 counting only the distinct ones).

The product of its digits is 1080, while the sum is 27.

The square root of 11561661 is about 3400.2442559322. The cubic root of 11561661 is about 226.1205728823.

It can be divided in two parts, 115 and 61661, that added together give a triangular number (61776 = T₃₅₁).

The spelling of 11561661 in words is "eleven million, five hundred sixty-one thousand, six hundred sixty-one".